1. Field of the Invention
This invention related to the field of primary batteries and, more specifically, to improved, lightweight fuel cells.
2. Description of the Prior Art
Fuel cells utilizing, for example, hydrogen and oxygen to create electricity are well known. The terminal potential of such a cell approximates only one volt and the current generating capacity is limited to several hundred milliamperes per square centimeter of electrode area. Thus, for practical use, it is necessary to connect multiple cells in series and parallel.
Such multi-layered cells, in the past, have utilized metallic plates, usually nickel, as separators between successive cells. Appropriate finger or other contacts were provided on the plates to inter-connect successive cell electrodes to provide series combination of the individual cells. Such construction suffered from excessive weight, which is undesirable in airborne or satellite operations, and from corrosion of the nickel separators. Further, with the temperature rise associated with fuel cell operation, differential expansion of the electrodes, separators and separator fingers resulted in increased electrical resistance within the layered cell and decreased overall performance for the battery.
The use of plastic separators has been suggested. In such construction graphite-impregnated connectors are molded integrally with the separators and extend through the separators to make electrical contact (when installed in a layered fuel-cell) between the anode of one cell and the cathode of the succeeding cell. It is necessary that such connectors be supported in vapor-sealed fashion within the separators so as to prevent undesired inter-leakage between the fuel and oxidizer compartments of successive cells. Regrettably, because of the significant difference in the coefficients of thermal expansion between such plastics as polyurethane, which might be used for the separators, and graphite with which the connectors are thoroughly impregnated, during the temperature rise normally associated with fuel cell operation, vapor leaking may occur where the connectors are supported in the separators and, further, contact between the conductors and successive fuel cell electrodes may show increased resistance, resulting in decreased battery performance.
Therefore, it is an object of this invention to eliminate the various problems set forth hereinbefore.
It is a further object of this invention to provide an improved layered fuel cell construction which is lightweight and easy to assemble.
It is an additional object of this invention to provide a layered fuel cell which shows high performance at elevated operating temperatures.